html,body{ 
      margin: auto;}
            @media screen and (min-width:300px) and (max-width:375px){html,body{ width:300px;
                      height:300px;
                      margin: auto;}}
            @media screen and (min-width:376px) and (max-width:414px){html,body{ width:350px;
                      height:350px;
                      margin: auto;}}
            @media screen and (min-width:415px) and (max-width:639px){html,body{ width:400px;
                      height:400px;
                      margin: auto;}}
            @media screen and (min-width:640px) and (max-width:719px){html,body{width:600px;
                      height:600px;
                      margin: auto;}}
            @media screen and (min-width:720px) and (max-width:749px){html,body{width:700px;
                      height:700px;
                      margin: auto;}}
            @media screen and (min-width:750px) and (max-width:799px){html,body{width:740px;
                      height:740px;
                      margin: auto;}}
            @media screen and (min-width:800px){
                 html,body{
                      width:800px;
                      height:800px;
                      margin: auto;}}
